The globally averaged temperature over land and ocean surfaces for 2014 was the highest among all years since record keeping began in 1880. The December combined global land and ocean average surface temperature was also the highest on record.
Global highlights: Calendar Year 2014
During 2014, the average temperature across global land and ocean surfaces was 1.24°F (0.69°C) above the 20th century average. This was the highest among all 135 years in the 1880–2014 record, surpassing the previous records of 2005 and 2010 by 0.07°F (0.04°C). Record warmth was spread around the world, including Far East Russia into western Alaska, the western United States, parts of interior South America, most of Europe stretching into northern Africa, parts of eastern and western coastal Australia, much of the northeastern Pacific around the Gulf of Alaska, the central to western equatorial Pacific, large swaths of northwestern and southeastern Atlantic, most of the Norwegian Sea, and parts of the central to southern Indian Ocean.
During 2014, the globally-averaged land surface temperature was 1.80°F (1.00°C) above the 20th century average. This was the fourth highest among all years in the 1880–2014 record. During 2014, the globally-averaged sea surface temperature was 1.03°F (0.57°C) above the 20th century average. This was the highest among all years in the 1880–2014 record, surpassing the previous records of 1998 and 2003 by 0.09°F (0.05°C). Looking above Earth’s surface at certain layers of the atmosphere, two different analyses examined NOAA satellite-based data records for the lower and middle troposphere and the lower stratosphere. The 2014 temperature for the lower troposphere (roughly the lowest five miles of the atmosphere) was third highest in the 1979-2014 record, at 0.50°F (0.28°C) above the 1981–2010 average, as analyzed by the University of Alabama Huntsville (UAH), and sixth highest on record, at 0.29°F (0.16°C) above the 1981–2010 average, as analyzed by Remote Sensing Systems (RSS). The 2014 temperature for the mid-troposphere (roughly two miles to six miles above the surface) was third highest in the 1979–2014 record, at 0.32°F (0.18°C) above the 1981–2010 average, as analyzed by UAH, and sixth highest on record, at 0.25°F (0.14°C) above the 1981–2010 average, as analyzed by RSS. The temperature for the lower stratosphere (roughly 10 miles to 13 miles above the surface) was 13th lowest in the 1979–2014 record, at 0.56°F (0.31°C) below the 1981–2010 average, as analyzed by UAH, and also 13th lowest on record, at 0.41°F (0.23°C) below the 1981–2010 average, as analyzed by RSS. The stratospheric temperature is decreasing on average while the lower and middle troposphere temperatures are increasing on average, consistent with expectations in a greenhouse-warmed world. According to data from NOAA analyzed by the Rutgers Global Snow Lab, the average annual Northern Hemisphere snow cover extent during 2014 was 24.95 million square miles, and near the middle of the historical record. The first half of 2014 saw generally below-normal snow cover extent, with above-average coverage later in the year. Recent polar sea ice extent trends continued in 2014. The average annual sea ice extent in the Arctic was 10.99 million square miles, the sixth smallest annual value of the 36-year period of record. The annual Antarctic sea ice extent was record large for the second consecutive year, at 13.08 million square miles.
Global highlights: December 2014
During December, the average temperature across global land and ocean surfaces was 1.39°F (0.77°C) above the 20th century average. This was the highest for December in the 1880–2014 record, surpassing the previous record of 2006 by 0.04°F (0.02°C). During December, the globally-averaged land surface temperature was 2.45°F (1.36°C) above the 20th century average. This was the third highest for December in the 1880–2014 record. During December, the globally-averaged sea surface temperature was 0.99°F (0.55°C) above the 20th century average. This was also the third highest for December in the 1880–2014 record. The average Arctic sea ice extent for December was 210,000 square miles (4.1 percent) below the 1981–2010 average. This was the ninth smallest December extent since records began in 1979, according to analysis by the National Snow and Ice Data Center based on data from NOAA and NASA. Antarctic sea ice during December was 430,000 square miles (9.9 percent) above the 1981–2010 average. This was the fourth largest December Antarctic sea ice extent on record. According to data from NOAA analyzed by the Rutgers Global Snow Lab, the Northern Hemisphere snow cover extent during December was 130,000 square miles below the 1981-2010. This was the 20th smallest December Northern Hemisphere snow cover extent in the 49-year period of record.
From The New York Times (Justin Gillis):
Several scientists said the most remarkable thing about the 2014 record was that it occurred in a year that did not feature El Niño, a large-scale weather pattern in which the ocean dumps an enormous amount of heat into the atmosphere.
Longstanding claims by climate-change skeptics that global warming has stopped, seized on by politicians in Washington to justify inaction on emissions, depend on a particular starting year: 1998, when an unusually powerful El Niño produced the hottest year of the 20th century.
With the continued heating of the atmosphere and the surface of the ocean, 1998 is now being surpassed every four or five years, with 2014 being the first time that has happened in a year featuring no real El Niño pattern. Gavin A. Schmidt, head of NASA’s Goddard Institute for Space Studies in Manhattan, said the next time a strong El Niño occurs, it is likely to blow away all temperature records…
“Obviously, a single year, even if it is a record, cannot tell us much about climate trends,” said Stefan Rahmstorf, head of earth system analysis at the Potsdam Institute for Climate Impact Research in Germany. “However, the fact that the warmest years on record are 2014, 2010 and 2005 clearly indicates that global warming has not ‘stopped in 1998,’ as some like to falsely claim.”
Such claims are unlikely to go away, though. John R. Christy, an atmospheric scientist at the University of Alabama in Huntsville who is known for his skepticism about the seriousness of global warming, pointed out in an interview that 2014 had surpassed the other record-warm years by only a few hundredths of a degree, well within the error margin of global temperature measurements.
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“Since the end of the 20th century, the temperature hasn’t done much,” Dr. Christy said. “It’s on this kind of warmish plateau.”
NASA and the other American agency that maintains long-term temperature records, the National Oceanic and Atmospheric Administration, issued separate data compilations on Friday that confirmed the 2014 record. A Japanese agency had released preliminary information in early January showing 2014 as the warmest year.
The last scientific group that curates the world’s temperature record, in Britain, is scheduled to report in the coming weeks.
“Why do we keep getting so many record-warm years?” Dr. Schmidt asked in an interview. “It’s because the planet is warming. The basic issue is the long-term trend, and it is not going away.”
February 1985 was the last time global temperatures fell below the 20th-century average for a given month, meaning that no one younger than 30 has ever lived through a below-average month.
The contiguous United States set its temperature record in 2012. But, mainly because of the unusual chill in the East last year, 2014 was only the 34th warmest year on record for the lower 48 states.
That cold was brought into the interior of the country by a loop in a current called the jet stream that allowed Arctic air to spill southward. But an offsetting kink allowed unusually warm tropical air to settle over the West, large parts of Alaska and much of the Arctic.
A few recent scientific papers say that such long-lasting kinks in the jet stream have become more likely because global warming is rapidly melting the sea ice in the Arctic, disturbing longstanding weather patterns. But many leading scientists are not convinced on that point.